Thanks for all the input. I understand the risks of towing and the liability U-Haul is trying to avoid. Actually if the guy had told me I couldn't pull the particular car I was wanting to pull with my truck that would not have bothered me, but honestly the discussion never got that far. As soon as mentioned Explorer, that was the end of the converstation, they won't rent anything towable to Explorers, not even the smallest trailer that they allow small cars to tow. The fact that they lumped the STs in the restriction with the SUVs. I bought the ST instead of the SUV because I knew it had a different chassis and did not have the rollover problems.
Anyway, we did getrdone. Daddy came and got us and we hooked it all up to his F-150. It was actually a pleasant afternoon. Three generations on a nice afternoon drive, and we stopped for a late lunch/early dinner.